Struct SyncEngineConfig 

pub struct SyncEngineConfig {

    pub redis_url: Option<String>,
    pub redis_prefix: Option<String>,
    pub sql_url: Option<String>,
    pub l1_max_bytes: usize,
    pub max_payload_bytes: usize,
    pub backpressure_warn: f64,
    pub backpressure_critical: f64,
    pub batch_flush_ms: u64,
    pub batch_flush_count: usize,
    pub batch_flush_bytes: usize,
    pub cuckoo_warmup_batch_size: usize,
    pub wal_path: Option<String>,
    pub wal_max_items: Option<u64>,
    pub wal_drain_batch_size: usize,
    pub cf_snapshot_interval_secs: u64,
    pub cf_snapshot_insert_threshold: u64,
    pub redis_eviction_enabled: bool,
    pub redis_eviction_start: f64,
    pub redis_eviction_target: f64,
    pub merkle_calc_enabled: bool,
    pub merkle_calc_jitter_ms: u64,
    pub enable_cdc_stream: bool,
    pub cdc_stream_maxlen: u64,
    pub redis_timeout_ms: u64,
    pub redis_response_timeout_ms: u64,
    pub sql_write_concurrency: usize,
    pub merkle_log_interval_secs: u64,
}

Configuration for the sync engine.

All fields have sensible defaults. At minimum, you should configure redis_url and sql_url for production use.

Fields

redis_url: Option<String>

Redis connection string (e.g., “redis://localhost:6379”)

redis_prefix: Option<String>

Redis key prefix for namespacing (e.g., “myapp:” → keys become “myapp:user.alice”) Allows sync-engine to coexist with other data in the same Redis instance.

sql_url: Option<String>

SQL connection string (e.g., “sqlite:sync.db” or “mysql://user:pass@host/db”)

l1_max_bytes: usize

L1 cache max size in bytes (default: 256 MB)

max_payload_bytes: usize

Maximum payload size in bytes (default: 16 MB)

Payloads larger than this will be rejected with an error. This prevents a single large item (e.g., 1TB file) from exhausting the L1 cache. Set to 0 for unlimited (not recommended).

Important: This is a safety limit. Developers should choose a value appropriate for their use case. For binary blobs, consider using external object storage (S3, GCS) and storing only references here.

backpressure_warn: f64

Backpressure thresholds

backpressure_critical: f64

batch_flush_ms: u64

Batch flush settings

batch_flush_count: usize

batch_flush_bytes: usize

cuckoo_warmup_batch_size: usize

Cuckoo filter warmup

wal_path: Option<String>

WAL path (SQLite file for durability during MySQL outages)

wal_max_items: Option<u64>

WAL max items before backpressure

wal_drain_batch_size: usize

WAL drain batch size

cf_snapshot_interval_secs: u64

CF snapshot interval in seconds (0 = disabled)

cf_snapshot_insert_threshold: u64

CF snapshot after N inserts (0 = disabled)

redis_eviction_enabled: bool

Redis eviction: enable proactive eviction before Redis LRU kicks in

redis_eviction_start: f64

Redis eviction: pressure threshold to start evicting (0.0-1.0, default: 0.75)

redis_eviction_target: f64

Redis eviction: target pressure after eviction (0.0-1.0, default: 0.60)

merkle_calc_enabled: bool

Merkle calculation: enable merkle tree updates on this instance.

In a multi-instance deployment with shared SQL, only a few nodes need to run merkle calculations for resilience. Set to false on most nodes. Default: true (single-instance default)

merkle_calc_jitter_ms: u64

Merkle calculation: jitter range in milliseconds.

Adds random delay (0 to N ms) before merkle batch calculation to reduce contention when multiple instances are calculating. Default: 0 (no jitter)

enable_cdc_stream: bool

CDC Stream: Enable Change Data Capture output to Redis Stream.

When enabled, every Put/Delete writes to {redis_prefix}:cdc. This enables external replication agents to tail changes. Default: false (opt-in feature)

cdc_stream_maxlen: u64

CDC Stream: Maximum entries before approximate trimming (MAXLEN ~).

Consumers that fall behind this limit rely on Merkle repair. Default: 100,000 entries

redis_timeout_ms: u64

Redis command timeout in milliseconds.

Maximum time to wait for a Redis command to complete before timing out. Under high load, increase this value to avoid spurious timeouts. Default: 5000 (5 seconds)

redis_response_timeout_ms: u64

Redis response timeout in milliseconds.

Maximum time to wait for Redis to respond after sending a command. Default: 5000 (5 seconds)

sql_write_concurrency: usize

Maximum concurrent SQL write operations.

Limits simultaneous sql_put_batch and merkle_nodes updates to reduce row-level lock contention and deadlocks under high load. Default: 4 (good balance for most MySQL setups)

merkle_log_interval_secs: u64

👎Deprecated since 0.2.0: Merkle tick removed; use cold path logging instead

Merkle diagnostic tick interval in seconds (DEPRECATED, no longer used).

Cold path logging now provides better visibility into merkle sync state. This field is retained for backwards compatibility with existing configs.

Trait Implementations

impl Clone for SyncEngineConfig

fn clone(&self) -> SyncEngineConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SyncEngineConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for SyncEngineConfig

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for SyncEngineConfig

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.